Other than mystic transmog, are there any possibilities of adding visual "stuff" directly to an item? For example..... A visually tweaked character with the item effect of fire on his head.... (Done via visual item in raw) can such a tweak be made to an item in the stash? Like a helm?

Visual tweaks go away when slot gets equipped. Hoping to bypass

Also, has anyone found a place in cky where once can view how many rift orbs have been collected?

If the name isn't in the list, no. The list uses names that are in game and sadly you cannot make your own names up. As for you trying to out effects on gear, sadly again no this will not happen. Only was is through the visual tab.